Search

Serum amyloid A (SAA) is an acute response protein that mainly produced by hepatocytes, and it can promote endothelial dysfunction via a pro-inflammatory and pro-thrombotic effect in atherosclerosis and renal disease. Overdose of Acetaminophen (APAP) will cause hepatotoxicity accompany with hepatocyte necrosis, liver sinusoidal endothelial cells (LSECs) damage and thrombosis in liver. However, whether SAA plays a role in APAP-induced liver toxicity remains unclear. Here, we evaluated the Saa1/2 expression in APAP-induced liver injury, and found that Saa1/2 production was significantly increased in an autocrine manner in APAP injury model. Moreover, we used neutralizing antibody (anti-SAA) to block the function of serum Saa1/2. We found that neutralizing serum Saa1/2 protected against APAP-induced liver injuries and increased the survival rate of mice that were treated with lethal dose APAP. Further investigations showed that blocking Saa1/2 reduced APAP-induced sinusoidal endothelium damage, hemorrhage and thrombosis. In addition, in vitro experiments showed that Saa1/2 augmented the toxic effect of APAP on LSECs, and Saa1/2 promoted platelets aggregation on LSECs cell membrane. Taken together, this study suggests that Saa1/2 may play a critical role in APAP-induced liver damages through platelets aggregation and sinusoidal damage. Therefore, we conceptually demonstrate that inhibition of SAA may be a potential intervention for APAP-directed acute liver injuries.

Our understanding of human hepatocellular carcinoma (HCC) development and progression has been hampered by the lack of in vivo models. We performed a genetic screen of 10 oncogenes and genetic mutations in Fah‐ablated immunodeficient mice in which primary human hepatocytes (PHHs) are used to reconstitute a functional human liver. We identified that MYC, TP53(R249S), and KRAS(G12D) are highly expressed in induced HCC (iHCC) samples. The overexpression of MYC and TP53(R249S) transform PHHs into iHCC in situ, though the addition of KRAS(G12D) significantly increases the tumorigenic efficiency. iHCC, which recapitulate the histological architecture and gene expression characteristics of clinical HCC samples, reconstituted HCC after serial transplantations. Transcriptomic analysis of iHCC and PHHs showed that MUC1 and FAP are expressed in iHCC but not in normal livers. Chimeric antigen receptor (CAR) T cells against these two surface markers efficiently lyse iHCC cells. The properties of iHCC model provide a biological basis for several clinical hallmarks of HCC, and iHCC may serve as a model to study HCC initiation and to identify diagnostic biomarkers and targets for cellular immunotherapy.

Liver regeneration is a complicated biological process orchestrated by various liver resident cells. Hepatic cell proliferation and reconstruction of the hepatic architecture involve multiple signaling pathways. It has been reported that the Hh signal is involved in liver regeneration. However, the signal transduction pathways and cell types involved are ill studied. This study aimed to investigate hedgehog signal response cell types and the specific molecular mechanism involved in the process of liver regeneration. Partial hepatectomy (PH) of 70% was performed on ICR (Institute of Cancer Research) mice to study the process of liver regeneration. We found that the hedgehog signal was activated significantly after PH, including hedgehog ligands, receptors and intracellular signaling molecules. Ligand signals were mainly expressed in bile duct cells and non-parenchymal hepatic cells, while receptors were expressed in hepatocytes and some non-parenchymal cells. Inhibition of the hedgehog signal treated with vismodegib reduced the liver regeneration rate after partial hepatectomy, including inhibition of hepatic cell proliferation by decreasing Cyclin D expression and disturbing the cell cycle through the accumulation of Cyclin B. The current study reveals the important role of the hedgehog signal and its participation in the regulation of hepatic cell proliferation and the cell cycle during liver regeneration. It provides new insight into the recovery of the liver after liver resection.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has become a global epidemic and poses a major threat to public health. In addition to COVID-19 manifesting as a respiratory disease, patients with severe disease also have complications in extrapulmonary organs, including liver damage. Abnormal liver function is relatively common in COVID-19 patients; its clinical manifestations can range from an asymptomatic elevation of liver enzymes to decompensated hepatic function, and liver injury is more prevalent in severe and critical patients. Liver injury in COVID-19 patients is a comprehensive effect mediated by multiple factors, including liver damage directly caused by SARS-CoV-2, drug-induced liver damage, hypoxia reperfusion dysfunction, immune stress and inflammatory factor storms. Patients with chronic liver disease (especially alcohol-related liver disease, nonalcoholic fatty liver disease, cirrhosis and hepatocellular carcinoma) are at increased risk of severe disease and death after infection with SARS-CoV-2, and COVID-19 aggravates liver damage in patients with chronic liver disease. This article reviews the latest SARS-CoV-2 reports, focusing on the liver damage caused by COVID-19 and the underlying mechanism, and expounds on the risk, treatment and vaccine safety of SARS-CoV-2 in patients with chronic liver disease and liver transplantation.

Summary The functional inactivation of tumor suppressor microRNA (miRNA) is closely related to the tumorigenesis of cancer. There are instances where the miRNA and the corresponding target both exist in a cell, but the target gene silencing do not occur as expected. Herein, we found that both miR-506 and its target CDK6 are highly co-expressed in lung cancer cells. Sequence analyses suggested that a miR-506 binding site (1648–1654) and a cis-element (1785–1795) for binding by heterogeneous nuclear ribonucleoprotein A2/B1 (HNRNPA2B1) are evolutionarily conserved and forms a stem structure in the 3′ untranslated region (3′UTR) of CDK6. Furthermore, HNRNPA2B1 can bind to the stem structure to denature it and recruit the RNA helicase DExH-box helicase 9 (DHX9) to the 3′UTR, which ultimately facilitates miRNAs-mediated CDK6 silencing. These results indicate that the cis-element of the 3′UTR of CDK6, where HNRNPA2B1 binds, serves as an RNA switch to regulate miRNAs’ function in cancer cells., Graphical abstract, Highlights • Both miR-506 and its target CDK6 are highly co-expressed in lung cancer • HNRNPA2B1 facilitates miR-506-mediated CDK6 silence by switching structure in 3′UTR • HNRNPA2B1 also recruits the DHX9 to the 3′UTR of its targets • HNRNPA2B1 extensively regulates miRNAs-mediated gene silencing through binding to 3′UTR, Biological sciences; Biochemistry; Molecular biology; Cell biology

An RNA switch is a regulatory cis-element, and its function is dependent on RNA structure transformation, which can be triggered by specific trans-factors, other regulatory RNAs and metabolites. There are instances where the microRNA (miRNA) and the corresponding target both exist in a cell, but the target gene silencing does not occur as expected. The mechanism behind this phenomenon is worth further investigation. Our research found that both miR-506 and its target cyclin dependent kinase 6 (CDK6) were highly co-expressed in multiple lung cancer cell lines. Sequence analyses suggested that a miR-506 binding site (1648-1654) and cis-element (1785-1795) for binding by heterogeneous nuclear ribonucleoprotein A2/B1(HNRNPA2B1) are evolutionarily conserved in the 3’ untranslated region (3’UTR) of CDK6, and form a stem structure that inactivates miR-506 function. HNRNPA2B1 denatures the stem structure to release the miR-506 binding site, leading to the recruitment of the miR-506-RISC complex for CDK6 silencing. HNRNPA2B1 also recruits the RNA helicase DExH-box helicase 9 (DHX9) to the 3’UTR of its targets, enhancing the engagement of argonaute RISC catalytic component 2 (AGO2) with the 3’UTR. This result indicates that the cis-element of the 3’UTR of CDK6 where HNRNPA2B1 binds serves as an RNA switch to regulate miRNA function. Deep understanding of the molecular basis of this phenomenon may provide novel biomarker and therapeutic targets for drug development.

Reprogramming has been shown to involve EMT–MET; however, its role in cell differentiation is unclear. We report here that in vitro differentiation of hESCs to hepatic lineage undergoes a sequential EMT–MET with an obligatory intermediate mesenchymal phase. Gene expression analysis reveals that Activin A-induced formation of definitive endoderm (DE) accompanies a synchronous EMT mediated by autocrine TGFβ signalling followed by a MET process. Pharmacological inhibition of TGFβ signalling blocks the EMT as well as DE formation. We then identify SNAI1 as the key EMT transcriptional factor required for the specification of DE. Genetic ablation of SNAI1 in hESCs does not affect the maintenance of pluripotency or neural differentiation, but completely disrupts the formation of DE. These results reveal a critical mesenchymal phase during the acquisition of DE, highlighting a role for sequential EMT–METs in both differentiation and reprogramming., Reprogramming has been shown to involve EMT-MET; however, its role in cell differentiation is unclear. Here the authors show that during in vitro differentiation of hepatocytes, Activin A-induced formation of definitive endoderm requires EMT mediated by TGFβ signalling, followed by a MET process.

The class III PI3-kinase (PIK3C3) is an enzyme responsible for the generation of phosphatidylinositol 3-phosphate (PI3P), a critical component of vesicular membrane. Here, we report that PIK3C3 deficiency in zebrafish results in intestinal injury and inflammation. In pik3c3 mutants, gut tube forms but fails to be maintained. Gene expression analysis reveals that barrier-function-related inflammatory bowel disease (IBD) susceptibility genes (e-cadherin, hnf4a, ttc7a) are suppressed, while inflammatory response genes are stimulated in the mutants. Histological analysis shows neutrophil infiltration into mutant intestinal epithelium and the clearance of gut microbiota. Yet, gut microorganisms appear dispensable as mutants cultured under germ-free condition have similar intestinal defects. Mechanistically, we show that PIK3C3 deficiency suppresses the formation of PI3P and disrupts the polarized distribution of cell-junction proteins in intestinal epithelial cells. These results not only reveal a role of PIK3C3 in gut homeostasis, but also provide a zebrafish IBD model., The functions of the class III PI3-kinase (PIK3C3) in gut homeostasis and innate immunity are poorly understood. Here the authors show that PIK3C3-deficient zebrafishes develop intestinal injury and inflammation due to mislocalization of cell junction proteins.

We report here an approach to redirecting somatic cell fate under chemically defined conditions without transcription factors. We start by converting mouse embryonic fibroblasts to epithelial-like cells with chemicals and growth factors. Subsequent cell fate mapping reveals a robust induction of SOX17 in the resulting epithelial-like cells that can be further reprogrammed to endodermal progenitor cells. Interestingly, these cells can self-renew in vitro and further differentiate into albumin-producing hepatocytes that can rescue mice from acute liver injury. Our results demonstrate a rational approach to convert mouse embryonic fibroblasts to hepatocytes and suggest that this mechanism-driven approach may be generalized for other cells.

The recombinant plasmid PGC was constructed for transcription unit of c-myc gene with diorientation in vitro , to make RNA probes for detection of c-myc mRNA and antisence RNA expression of tranfectant HL R 60 -9, which was obtained from HL60 cells transfected with inducible c-myc antisense RNA expression plasmid. The results from HL R 60 -9 cells induced by Cd 2+ indicated that expression of c-myc antisense RNA increased with Cd 2+ concentration and exposure time, while c-myc mRNA expression progressively reduced. Using immunohistochemical technique no c-myc P62 protein expression was detected. The incorporation of 3 H-TdR, 3 H-UR and 3 HLeu revealed significant suppression of DNA, RNA and protein biosynthesis. It is suggested that the reversion changes previously reported in malignant phenotypes of HL R 60 -9 cells and the inhibition of macromolecular biosynthesis mentioned above were associated with the blockade of c-myc gene expression by its antisense RNA.

Accumulating evidence indicates that the mesenchymal-epithelial transition (MET) and epithelial-mesenchymal transition (EMT) are basic mechanisms for cell fate conversion and may help us understand both physiologic and pathologic processes such as development and carcinogenesis. Here, we further suggest that mammalian cells fall into two grand divisions, mesenchymal or epithelial; interconversions between these two grand divisions through EMT/MET resonate with some ancient Chinese philosophic ideas.